Rapid nitrification with immobilized cell using macro-porous cellulose carrier

Macro-porous cellulose carrier (AQUACEL) was applied for immobilization of nitrifying bacteria to develop a practical nitrogen removal system. The results of nitrification experiments revealed that both particle and pore sizes of the carrier significantly influenced the nitrification process. When the optimized carrier (particle size of 1 mm and pore size of 500 μm) was employed, the complete ammonium oxidation was attained at a high ammonium loading rate of 12 kg-N•m−3-carrier•d−1 at 25°C. In the nitrification using 5 mm cubic carrier, the accumulation of ammonium and nitrite ions resulting from complete inhibition of nitrite oxidation occurred at an ammonium loading rate of 10 kg-N•m−3-carrier•d−1. By measuring oxygen effectiveness factor of immobilized cells, the oxygen transfer inside the macro-porous carriers was found to be enhanced by liquid convection.